of/device: Replace struct of_device with struct platform_device

of_device is just an alias for platform_device, so remove it entirely.  Also
replace to_of_device() with to_platform_device() and update comment blocks.

This patch was initially generated from the following semantic patch, and then
edited by hand to pick up the bits that coccinelle didn't catch.

@@
@@
-struct of_device
+struct platform_device

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: David S. Miller <davem@davemloft.net>

drivers/watchdog/cpwd.c

@@ -526,7 +526,7 @@ static const struct file_operations cpwd_fops = {
 	.release =		cpwd_release,
 };
 
-static int __devinit cpwd_probe(struct of_device *op,
+static int __devinit cpwd_probe(struct platform_device *op,
 				const struct of_device_id *match)
 {
 	struct device_node *options;
@@ -639,7 +639,7 @@ out_free:
 	goto out;
 }
 
-static int __devexit cpwd_remove(struct of_device *op)
+static int __devexit cpwd_remove(struct platform_device *op)
 {
 	struct cpwd *p = dev_get_drvdata(&op->dev);
 	int i;